Project Summary/Abstract Peru is affected by a concentrated HIV epidemic, in which men who have sex with men (MSM) and transgender women (TW) are most affected. For the past nine years, Peru has received funding from four Global Fund financing rounds to support the national response to the epidemic. This allowed the introduction of free ART in public hospitals, increased condom distribution, and strengthened community organizations. While these efforts succeeded in increasing access to treatment and reducing HIV related morbidity and mortality, it is unclear to what extent prevention work has had a positive impact; in fact, HIV incidence among MSM and TW seems to have remained stable. Despite substantial HIV-focused research in Peru over the past 15 years, research has mainly consisted of clinical trials of international interest that have not supported local HIV prevention programs. This planning proposal seeks to develop a training program in HIV population science and strengthen institutional capacities to prepare grant applications and manage/regulate funded studies. It is led by the Unit of Health, Sexuality and Human Development at Cayetano Heredia University (UPCH) in collaboration with the Universities of California at Berkeley, Los Angeles and San Francisco. The main areas for this proposed training are: epidemiological surveillance, studies of psychosocial and structural determinants of risk and vulnerability; implementation studies of combination (biomedical, behavioral, structural) prevention; and policy studies oriented to understand and improve the use of evidence for HIV policy making. This training program is conceived as synergistic and complementary with other training initiatives ongoing or planned at UPCH and other institutions in Peru.